New clear thinking on risky business

Weighing the benefit of clean energy against the risk of another nuclear disaster has pushed the thinking of many scientists previously opposed to nuclear power into the pro-nuclear camp (Source: MartinLister/iStockphoto)

Risk is perhaps the most difficult concept to communicate because what you make of it depends heavily on your perspective.

In science, risk can be calculated as a statistic, a probability of an event occurring. Whereas, to an individual, risk is something personal — it's the possibility of an event effecting them no matter how remote the probability of that event actually taking place.

Science calculates the risk of dying in a plane crash to be vanishingly small where as an individual wonders what it would be like for it to happen to them. For science risk is objective, for individuals it's visceral.

And, as we shall see, perception of risk can depend heavily on the issues at stake. Why do we look at the risk from nuclear power generation in a different light to far riskier activities such as driving a car or flying in an aeroplane?

A working formulation of the Precautionary Principle is; "If an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of scientific consensus that the action or policy is not harmful, the burden of proof that it is not harmful falls on those taking an action".

But the popular misconception of the Precautionary Principle is that, if there is a risk in a particular action, then don't do it. That formulation is unworkable in the real world because there is risk associated with every action and, as you can see, the Precautionary Principle is more subtle than that. It's a tool for weighing risks against benefits to determine if a course of action is worthwhile.

An important qualifier in the Precautionary Principle is the phrase "in the absence of scientific consensus".

But I find the concept of a consensus in science is meaningless — it doesn't matter how many scientists agree on a subject, they could all be shown to be wrong with a single observation.

A more useful concept is consilience — do independent lines of research come to the same conclusion and, if so, what is the weight of evidence, the quantity of research, that supports that idea?

So perhaps we can modify the above description of the Precautionary Principle with a simple substitution of "consilience" for "consensus".

"If an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of a body of scientific knowledge that the action or policy is not harmful, the burden of proof that it is notharmful falls on those taking an action'.

More simply, if you don't know what's going to happen or if you can't demonstrate that an action will do no harm, then don't do it.

That's why you don't have to invoke the Precautionary Principle in discussions where there is a clear consilience and where the science is sound. For example, climate change.

There is an overwhelming consilience of evidence (hundreds or even thousands of independent lines of research) that releasing more carbon into the atmosphere will have harmful effects, so therefore we should not do it. We're not taking a precaution here, we're acting on the best quality science for the betterment of people and the environment.

But what about issues where there is no scientific consilience or the consilience is unclear?

That's where the Precautionary Principle does come into play to help us to determine what we should and shouldn't do. And, as more scientific data is bought into the discussion, that equation of risk will change along with its prescription for action. A good example concerns nuclear power.

Nuclear or not?

Historically there have been two scientific consiliences with respect to the safety and viability of nuclear power generation.

Broadly speaking physicists, the 'hard' sciences and engineers have advocated that nuclear energy can generate cheap power and do so safely if properly managed. But the other consilience lead by biologists (particularly ecologists) has argued the opposite case, that even though harmful events from nuclear power stations may be extremely rare, the impact when they do occur is too great to warrant taking that risk. As long as both sides can support their arguments with independent lines of research, there will be these two conflicting consiliences with no objective measure that allows us to pick one over the other.

This broad characterisation of the landscape of scientific research on nuclear power has changed quite radically over the last decade or so, and it has changed because a broader scope of scientific data has been introduced into the discussion.

Sure, in the public eye, the greatest influence on the nuclear power debate has been the disasters at Chernobyl and Fukushima, but to focus on these events is to miss the bigger picture. It's akin to having a discussion about the merits of international air travel and only discussing the plane crashes. This skewing of the discussion has not been helped by some particularly poor reporting in the media with reporters running away from exclusion zones when their Geiger Counters go off. Invariably those same reporters were exposed to much higher levels of radiation on the plane flights to Japan or the Ukraine to cover the story.

Within science, the shift in consilience has been toward approving of the adoption of nuclear power by the ecologists, biologists and environmentalists who were originally opposed to it. This shift in attitude is neatly explored in the documentary Pandora's Promise and centres around the growing awareness of the need to adopt energy sources that don't pump more carbon dioxide into the air.

So, weighing the benefit of abundant, carbon-free energy against the risk of another nuclear disaster has pushed the thinking of many scientists previously opposed to nuclear power into the pro-nuclear camp. Do have a look at the blogs of ecologists such as Barry Brook for a perfect illustration of how some scientists minds have changed on the nuclear question.

There are plenty of other issues at play within the science behind the questions of nuclear power, much more than I can delve into here. But it is interesting to see how the balance between the two conflicting consiliences has changed and it's all because a greater scope of data has been injected into the discussion.

From where I sit as an observer on the debate, it looks like the proponents for nuclear power are mustering the data that show that a nuclear power industry can be operated in a way that will do no harm and thus they can legitimately reject the Precautionary Principle. Adding weight to their case is the need to derive large quantities of carbon-free energy which nuclear options can do alongside a variety of renewable options.

Yes, there's a risk in going down the nuclear path, there will always be a risk in any course of action, but the certainty of doing great damage to our health and that of the planet by continuing to burn fossil fuels demands that we do something different.

Does this change in scientific environment mean that a nuclear future can clear the Precautionary Principle? That's the debate that we have to have.

About the author:Dr Paul Willis is the director of RiAus, Australia's unique national science hub, which showcases the importance of science in everyday life. The well-known palaeontologist and broadcaster previously worked for ABC TV's Catalyst program.